Supporting roller

ABSTRACT

A supporting roller ( 12, 122, 123 ) that has a greater than usual capacity for constant operation comprises a skirt ( 14 ), for supporting a return side ( 16 ) of an endless chain of a chain conveyor, and, coaxial with the skirt ( 14 ), a hub ( 18 ) designed to rotate idly on a journal ( 19 ), and, in addition, a sleeve ( 20 ) made of a material having high friction laid over the skirt ( 14 ), in particular overmolded around the skirt ( 14 ) or slid axially onto the skirt ( 14 ).

CROSS-REFERENCE TO RELATED APPLICATIONS

[0001] This applications claims priority to European patent applicationNo. 00830352.1 filed May 16, 2000.

FIELD OF THE INVENTION

[0002] The subject of the present invention is a supporting roller.

BACKGROUND OF THE INVENTION

[0003] One known type of supporting roller comprises a skirt, forsupporting a return side of a chain of a conveyor, and, coaxial with theskirt, a hub designed to rotate idly on a journal.

[0004] Though in many ways satisfactory, known rollers leave much to bedesired when it comes to durability of operation.

[0005] One of the main problems with known rollers is that they tend, asthey rotate about their respective journals, to pick up impurities, suchas particles resulting from wear, and dirt in general, which greatlyincrease the resistance to rotation of the supporting roller on thejournal. Because of the increasing resistance to rotation presentbetween the known roller and the journal, the return side of the chaintends to skid on the surface of the skirt, resulting in accelerated wearof the parts in contact with each other.

[0006] Another problem with known rollers, especially under theconditions of use at high speeds of rotation of the chain, is the noiseof the coupling between the skirt and the chain.

[0007] The problem addressed by the present invention is to devise asupporting roller with structural and functional characteristics such asto overcome the abovementioned problems cited with reference to theprior art.

SUMMARY OF THE INVENTION

[0008] This problem is solved with a supporting roller of the typespecified above, characterized in that a sleeve made of a materialhaving high friction is laid over the skirt.

[0009] Specifically, the invention is a supporting roller of the typecomprising a skirt, for supporting a return side of an endless chain ofa chain conveyor, and, coaxial with the skirt, a hub designed to rotateidly on a journal, wherein it comprises a sleeve made of a materialhaving high friction laid over the skirt.

[0010] The invention also provides a support for a return side of anendless conveyor chain, comprising at least two supporting rollersrotating idly side by side on a journal, wherein each roller includes ahub mounted on the journal and supporting a skirt on which is disposed afriction sleeve.

BRIEF DESCRIPTION OF THE DRAWINGS

[0011] Further features and the advantages of the supporting rolleraccording to the present invention will appear from the descriptiongiven below of a preferred embodiment thereof, provided by way ofnon-restrictive indication, with reference to the accompanying figuresin which:

[0012]FIG. 1 is a perspective view of a supporting roller;

[0013]FIG. 2 is a side view of the supporting roller shown in FIG. 1;

[0014]FIG. 3 is an axial section through the roller shown in FIG. 2,taken on III-III;

[0015]FIG. 4 is an axial section through the roller shown in FIG. 2,taken on IV-IV;

[0016]FIG. 5 is a side view of the roller shown in FIG. 4, in thedirection of the arrow V;

[0017]FIG. 6 is a perspective view, with separated parts, of a stage inthe assembly of the roller of FIG. 1;

[0018]FIG. 7 is a perspective view of a supporting roller in a secondembodiment;

[0019]FIGS. 8, 9 and 10 are side views of three embodiments ofsupporting means comprising two supporting rollers;

[0020]FIG. 11 is a side view of a supporting roller in a thirdembodiment;

[0021]FIG. 12 is an axial section through the roller shown in FIG. 11,taken on XII-XII;

[0022]FIG. 13 is an axial section through the roller shown in FIG. 11,taken on XIII-XIII;

[0023]FIG. 14 is a side view of the roller shown in FIG. 13, in thedirection of arrow XIV;

[0024]FIG. 15 is an axial section similar to that of FIG. 12 showing acomponent of the supporting roller of FIGS. 11-14, in an intermediatestage of the production process;

[0025]FIG. 16 is a section through the component of FIG. 15, taken onXVI-XVI;

[0026]FIG. 17 is an axial section taken on XVII-XVII through thecomponent shown in FIG. 15, at a later stage in the production process;and

[0027]FIG. 18 is a perspective view, with separated parts, of a stage inthe assembly of the roller of FIGS. 11-17.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0028] Referring to the accompanying figures, the number 12 is a generalreference for a supporting roller of axis X-X that comprises a skirt 14designed to offer support to a return side 16 of an endless chain of achain conveyor (shown in the figures in chain lines), and a hub 18,coaxial with the skirt 14 and designed to be slid axially onto a journal19. The term “skirt” here denotes a supporting structure comprising anintermediate bush 15 with a cylindrical outer surface 15 a capable ofsupporting the chain 16 as it advances.

[0029] Advantageously, a sleeve 20 made of material with high friction,meaning a sleeve made of a material with a high coefficient of friction,is laid over the skirt 14. It is particularly advantageous for thesleeve 20 to be slid axially onto the cylindrical outer surface 15 a ofthe skirt 14. The said sleeve 20 covers all the cylindrical outersurface 15 a and so comes between the chain 16 and the intermediate bush15.

[0030] The sleeve 20 with high friction is preferably composed of amaterial selected from the natural or synthetic elastomers and inparticular is of rubber.

[0031] Also advantageously, the sleeve 20 is held tightly between twoopposing shoulders 22, 24 and preferably between a first shoulder 22 anda second shoulder 24 provided on the skirt 14 and on the hub 18respectively, as will be detailed hereinbelow. Near one end 26 of thehub 18 is an annular wall 28. This wall 28 has a radial relief 30 orshoulder forming the said second shoulder 24 by which the sleeve 20 isheld. Integral with the cylindrical bush 15 of the skirt 14 is an endwall 32 situated at the opposite end from the annular wall 28 of the hub18. This wall 32 is annular, so that the roller 12 can be slid axiallyonto the journal 19. The surface of the free end of the bush 15 is thefirst shoulder 22 by which the sleeve 20 is held. At the end 33 of thesleeve 20 nearest and facing the annular wall 28 is an inward annularprojection 34 on which the said opposing shoulders 22, 24 are to act.The width of the annular projection 34 is greater than the minimumdistance achievable between the shoulders 22 and 24 after their closure.

[0032] The main advantages of the invention lie in the fact that theside 16 of the chain rolling (arrow h) over the sleeve 20 of materialwith a high coefficient of friction exerts a large tangential action(arrow i) on the supporting roller 12 but overcomes the resistancecaused by the impurities that collect between the roller 12 and thejournal 19, thus ensuring precise skid-free rolling and withoutaccelerated wear of the components in contact with each other (FIG. 1).

[0033] It is also an advantage that the sleeve 20 is held betweenopposing shoulders 22, 24, thus ensuring that the sleeve 20 is clampedand anchored firmly to the skirt 14 and to the hub 18 so that it willwithstand the stresses produced by the section 16 of chain in motion.Moreover, this tight holding of the sleeve 20 creates a perfect seal,preventing impurities from getting inside the roller 12. By virtue ofthis embodiment of the invention, the tight closure occurs against theannular projection 34, which has small longitudinal dimensions comparedwith the overall dimensions of the sleeve 20, which fact makes itpossible to have highly precise coupling even with not very highprocessing tolerances, as in the case of large-scale production.

[0034] Another advantage is that, owing to the presence on the skirt 14of the sleeve 203 of elastomeric material, the coupling between thechain and the roller is noiseless, even at the high speeds of rotationof the chain.

[0035] In order to prevent a sideways action relative to the supportingroller 12 from pushing the sleeve 20 off, it is advantageous if theannular wall 28 of the hub 18 and the end wall 32 of the skirt 14 extendpartially against the sides of the sleeve 20 so that the sleeve ispartially embraced by a containment seat 36.

[0036] To prevent sideways movements of the chain 16 as it rolls overthe roller, it is advantageous too if a retaining flange 38 extendsradially from one end of the supporting roller 12. For example, theflange 38 is formed as a radial extension of the annular wall 28 of thehub 18.

[0037] In order that the sleeve 20 can be slid axially onto the skirt 14and the annular projection 34 be held tightly, the hub 18 advantageouslyfits telescopically into the skirt 14. More specifically, a plurality ofspokes 40 extend inwards from the bush 15 and join a tube 42 positionedcoaxially with the skirt 14 and forming a seat 44 for the hub 18 (FIG.6).

[0038] If using a supporting roller 12 comprising a hub 18 that fits theskirt 14 telescopically, it is advantageous to produce the hub 18 inacetal resin and the skirt 14 in polypropylene, in order to ensure goodmechanical strength and at the same time reduce costs.

[0039] Advantageously, the hub 18 and the skirt 14 are connected bysnap-connection means. The sleeve 20, held between the skirt 14 and thehub 18, which are connected by the snap-connection means, is preloaded.For example, the skirt 14 has at least one seat 46 for receiving atleast one tooth 48 projecting from the hub 18. The seats 46 arepreferably slots formed transversally in the bush 15, into which teeth48 formed on the ends of elastic brackets 50 extending longitudinallyfrom the annular wall 28 of the hub 18, engage with a snap action fromthe inside of the bush 15.

[0040] For correct angular location of the hub 18 with respect to theskirt 14, the tube 42 contains at least one longitudinal slot 52 forreceiving a relief 54 on the outside of the hub 18 (FIG. 6). The relief54 of the hub 18 and the slot 52 of the tube 42 are arranged so as toalign the teeth 48 projecting from the hub 18 with the slots 46 formedin the skirt 14, for a correct engagement.

[0041] The sleeve 20 is advantageously slid axially onto the skirt 14 toprovide an interference fit, which facilitates the transfer of thetangential action produced by the rolling of the chain from the sleeve20 to the skirt 14 and thence to the hub 18. To still further advantage,the sleeve 20 is fixed integrally to the skirt 14 by the provision of aplurality of longitudinal projections 55 formed on the outside of theskirt (FIG. 6).

[0042] In order to prevent impurities from penetrating between the hub18 and the tube 42 and filling the space 58 defined by the tube 42, endwall 32 and intermediate bush 15, as well as by the annular wall 28 ofthe hub 18, a relief 60 is provided in the tube 42 at the opposite endfrom the said annular wall 28 and engages in the outer wall of the hub18 (FIG. 4). The proposed supporting roller 12 is therefore morehygienic and does not require repeated and frequent dismantling forcleaning purposes.

[0043] As can be seen in FIG. 7, it is possible and advantageous toprovide a supporting roller 122 according to the invention without thechain 16-retaining flange 38. This means that it is possible to providesupporting means for the return side of an endless chain of a conveyor,the said means comprising at least two flanged 38 rollers 12 arrangedsymmetrically and rotating idly on the journal 19 (FIG. 8).Alternatively, the said means may comprise at least one supportingroller 122 with no flange (FIG. 9), or the supporting means may comprisea supporting roller 12 with a retaining flange 38 and a roller 122without this flange (FIG. 10).

[0044] The operation of the supporting roller will now be described withthe assistance of FIGS. 1 and 6.

[0045] The hub 18 is fitted into the inside of the tube 42, and tightlycloses (in the direction of arrow g in FIG. 6) the sleeve 20 which hasalready been slid axially (in the direction of arrow f) onto the sleeve14. Because of the sleeve 20, which is made of a material with highfriction, the supporting roller 12 is stressed, under the weight of asection of the chain 16 in motion (arrow h) with a tangential actionsufficient to overcome the rolling resistance due to impuritiesaccumulated on the journal.

[0046] FIGS. 11 to 18 illustrate a further embodiment of a supportingroller 123 in accordance with the present invention. In these figures,parts identical or similar to those previously described will beidentified by the same numerical references.

[0047] The peculiarity of the roller 123 in this further embodiment ofthe invention lies first of all in the fact that it is provided with asleeve 203 which is not simply slid axially onto the skirt 14 butovermoulded directly around it, by injection of material in liquid phaseinto a mould containing the skirt 14, around the cylindrical outersurface 15 a of the skirt 14.

[0048] The slots 46, provided in the skirt 14 to accommodate the teeth48 projecting from the hub 18 to bring about the snap connection betweenthe skirt 14 and the hub 18, extend into the thickness of the bush 15but not all the way through the thickness of this bush 15, in otherwords the slots 46 do not break through onto the cylindrical outersurface 15 a: the cylindrical outer surface 15 a of the bush 15therefore has no openings and is essentially continuous.

[0049] The end wall 32 of the skirt 14 preferably does not extendradially beyond the cylindrical outer surface 15 a of the skirt 14, andstops more or less flush with the said surface 15 a. In other words, thecontainment seat 36 for the sleeve 203 is not formed. Also, the sleeve203 not only extends over the cylindrical outer surface 15 a of theskirt but also continues past a circular edge 320 between the bush 15and the end wall 32 to form a discoidal covering 204 which clings to andcovers the outside of the end wall 32 of the skirt 14. The discoidalcovering 204 extends as far as the edge of the central opening of thetube 42. In this way the face 204 acts as a seal against the hub 18,preventing dirt from working in between the hub and tube 42.

[0050] In order to produce the sleeve 203, the skirt 14 (FIGS. 15 and16) is first made and then inserted into a mould, and the elastomericmaterial which will form the sleeve 203 is injected into this mould inthe liquid phase in such a way as to overmould the sleeve 203 and theface 204 directly onto the skirt 14. A substantially single component143, shown in FIG. 17, is thus obtained in which the sleeve 203 isfirmly fixed to the skirt 14. The hub 18 can then be coupled to thecomponent 143 in the same way as described earlier with reference to thefirst two embodiments. The sleeve 203 is thus again held tightly betweenthe opposing shoulders 22, 24.

[0051] Given the right apparatus, the skirt 14 and the sleeve 203 canalso be made by co-injecting the two different materials into a suitablemould.

[0052] Examples of suitable materials from which to make the roller 123are polypropylene for the skirt 14 and thermoplastic rubber EPDM for thesleeve 203; alternatively the skirt 14 can be made in ABS, and thesleeve 203 in thermoplastic polyurethane rubber. Other materials can ofcourse be used, as will be obvious to those skilled in the art.

[0053] Producing the sleeve 203 by overmoulding it directly onto theskirt 14 not only simplifies the operations of assembly of the roller,which is now therefore composed of two components (the hub and thecombined skirt and sleeve) instead of three as in the earlierembodiments, but also offers a better guarantee, compared to the simpleinterference fit, that the tangential action produced by the rolling ofthe chain will be transmitted to the skirt 14 and so to the hub 18.

[0054] It should be observed that the roller 123 in accordance with thisfurther embodiment can also be modified in such a way as to eliminatethe flange 38, thus giving a structure similar to that of FIG. 7, andtherefore making the variety of configurations shown in FIGS. 8, 9 and10 possible.

[0055] A person skilled in the art could, of course, in order to satisfyparticular and specific requirements, make numerous modifications andalterations to the supporting roller described above that wouldnonetheless all remain within the scope of protection of the inventionas defined in the following claims.

What is claimed is:
 1. A supporting roller of the type having a skirt,for supporting a return side of an endless chain of a chain conveyorand, coaxial with the skirt, a hub designed to rotate idly on a journal,wherein the roller comprises a sleeve made of a material having highfriction laid over the skirt.
 2. The supporting roller according toclaim 1, wherein the sleeve is overmoulded around the skirt.
 3. Thesupporting roller according to claim 1, wherein the sleeve is slidaxially onto the skirt.
 4. The supporting roller according to claim 3,wherein a plurality of projections are formed on the outside of theskirt to act on the inside of the sleeve.
 5. The supporting rolleraccording to claim 2, 3 or 4, wherein the sleeve laid over the skirt isheld between opposing shoulders.
 6. The supporting roller according toclaim 5, wherein the sleeve is held tightly between a first shoulder andan opposing second shoulder.
 7. The supporting roller according to claim6, wherein the roller has an annular wall near one end of the hubforming the second shoulder for holding the sleeve.
 8. The supportingroller according to claim 7, wherein it comprises the first shoulder,for holding the sleeve, at one end of the skirt.
 9. The supportingroller according to claim 8, wherein the inside of the sleeve has anannular projection on which the opposing holding shoulders can act. 10.The supporting roller according to claim 1, wherein the hub fitstelescopically into the skirt.
 11. The supporting roller according toclaim 10, wherein a plurality of spokes extend inwards from the skirtand join a tube positioned coaxially with the skirt and forming a seatfor the hub.
 12. The supporting roller according to claim 11, wherein anend wall of the skirt extends from the latter towards the tube.
 13. Thesupporting roller according to claim 12, wherein the sleeve isovermoulded around the skirt and extends over the end wall of the skirtso that it covers it externally.
 14. The supporting roller according toclaim 1, wherein the hub and the skirt are connected by a snapconnection.
 15. The supporting roller according to claim 14, whereinthere is at least one seat in the skirt for at least one toothprojecting from the hub to snap into to form the said snap connection.16. The supporting roller according to claim 15, wherein there are oneor more teeth at the end of at least one bracket extendinglongitudinally from an annular wall near one end of the hub.
 17. Thesupporting roller according to claim 14, further including at least onelongitudinal slot for receiving an angle-locating relief on the outsideof the hub.
 18. The supporting roller according to claim 1, wherein thehub includes a chain-retaining flange.
 19. The supporting rolleraccording to claim 2, wherein the sleeve is of an elastomer.
 20. Thesupporting roller according to claim 3, wherein the sleeve is of anelastomer.
 21. The supporting roller according to claim 2, wherein thesleeve is rubber.
 22. The supporting roller according to claim 21,wherein the sleeve is a thermoplastic rubber.
 23. The supporting rolleraccording to claim 22, wherein the said thermoplastic rubber is selectedfrom the group consisting of EPDM and polyurethane.
 24. The supportingroller according to claim 3, wherein the sleeve is rubber.
 25. Thesupporting roller according to claim 24, wherein the sleeve is athermoplastic rubber.
 26. The supporting roller according to claim 25,wherein the said thermoplastic rubber is selected from the groupconsisting of EPDM and polyurethane.
 27. The supporting roller accordingto claim 1, wherein the hub is made of acetal resin.
 28. The supportingroller according to claim 2, wherein the skirt is a made of a plasticselected from the group consisting of polypropylene and ABS.
 29. Thesupporting roller according to claim 3, wherein the skirt is a made of aplastic selected from the group consisting of polypropylene and ABS. 30.A support for a return side of an endless conveyor chain, comprising atleast two supporting rollers rotating idly side by side on a journal,wherein each roller includes a hub mounted on the journal and supportinga skirt on which is disposed a friction sleeve.
 31. The supportaccording to claim 30, wherein at least one of the supporting rollershas a chain-retaining flange.